title: Levamisole resistance in Trichostrongylus colubriformis: a sex-linked recessive character.
abstract: Reciprocal crosses between susceptible and levamisole resistant strains of Trichostrongylus colubriformis produced F1 offspring consistent with resistance being inherited as a sex-linked recessive character. The resistance status of the offspring of the backcrosses of the F1 to both parental strains supported this hypothesis. The results are consistent with resistance being controlled by a single gene, or a tightly linked group of genes, but indicate that other autosomal loci have minor effects. The results contrast with the reported observations that resistance to the benzimidazole anthelmintics is polygenic and autosomal. The results are discussed relative to a general evolutionary model for anthelmintic resistance which predicts that selection from the upper extreme of an anthelmintic tolerance distribution results in polygenicity.
authors.affiliation: CSIRO Division of Animal Health, Animal Health Research Laboratory, Parkville, Victoria, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Martin
authors.forename: J A
authors.initials: JA
authors.lastname: McKenzie
mesh_terms: D000818:Animals; D004351:Drug Resistance / Q000235:genetics; D005260:Female; D005808:Genes, Recessive; D008040:Genetic Linkage; D007978:Levamisole / Q000494:pharmacology*; D008297:Male; D014254:Trichostrongylus / Q000187:drug effects* / Q000235:genetics
chemical_list: D007978:Levamisole